Arrector Pili Muscles (Hair Erector Muscles): What Do They Have to Do with Hair Loss?

Many people think of hair loss simply as "a phenomenon where hair falls out."

In fact, hair loss is a complex process that includes changes in the structure of hair follicles as well as the loss of the arrector pili muscle (hair erector muscle, Arrector Pili Muscle).

The arrector pili muscle is a small muscle connected to the hair follicle, and it is the muscle that causes goosebumps and makes hair stand up when we are cold.

But did you know that this arrector pili muscle gradually disappears as hair loss progresses?

Arrector pili muscle (hair erector muscle)

(Source: Hair Science: All About Non-Surgical Hair Loss Treatment and Non-Incisional Hair Transplantation, Kim Jin-oh et al.

Gunja Publishing | January 20, 2025)

While the arrector pili muscle is present, the hair follicle is more likely to remain in a relatively healthy state.

However, once the arrector pili muscle is lost, that hair follicle is no longer likely to recover and is more likely to progress to a stage where it ultimately disappears completely.

This is not just a matter of the hair becoming thinner; it is a process in which the hair follicle itself loses its function.

According to research, if treatment is started while the arrector pili muscle is still preserved, it may be possible to prevent the progression of hair loss or achieve some degree of recovery. However, after the arrector pili muscle has completely disappeared, even medication is unlikely to be effective.

The most important thing in hair loss treatment is early intervention.

If treatment begins before the arrector pili muscle is lost, the chances of restoring hair follicle function are higher.

Representative treatment methods include the following.

1. Finasteride & Dutasteride

• They inhibit DHT (dihydrotestosterone), helping prevent follicular miniaturization and helping the arrector pili muscle remain intact.

2. Minoxidil

• By dilating blood vessels, it increases nutrient delivery to the hair follicles and is more likely to be effective while the arrector pili muscle is still preserved.

3. PRP (Platelet-Rich Plasma) Therapy

• By directly injecting growth factors into the scalp, it may help activate hair follicles and prevent degeneration of the arrector pili muscle.

4. Low-Level Laser Therapy (LLLT, Low-Level Laser Therapy)

• Research findings indicate that it helps stimulate hair follicles so the arrector pili muscle can maintain its function.

Many hair loss patients think, "I still have hair, so I should wait a little longer."

However, since no treatment is likely to be effective after the arrector pili muscle has completely disappeared, it is important to start treatment as early as possible.

If you notice that the hair at the temples or the vertex is becoming thinner, there is a high chance that weakening of the arrector pili muscle is already underway.

If the amount of hair falling out when you wash your hair has increased compared with usual, it is a good idea to consult a specialist right away.

The key to hair loss treatment is to start quickly while the arrector pili muscle is still present.

As time passes, the hair follicles themselves may degenerate, and in the end, hair transplantation may be the only option.

Therefore, if you suspect hair loss, the best approach is to consult a specialist immediately and respond early.

It's time for hair growth, this was Kim Jin-oh.

Pilsaengsinmo (必生新毛).

[This post is written directly by a plastic surgery specialist for the purpose of providing information in accordance with Article 56, Paragraph 1 of the Medical Service Act. Hair loss surgery and treatment may have side effects, and you should make a careful decision through consultation with a specialist.]